Fluoroperhalocarbon liquids (e.g., perfluorinated liquids) have many industrial uses, such as coolants for electronic devices (e.g., supercomputers) and as heat transfer media in vapor-phase soldering processes. However, upon heating many of these liquids at high temperatures, toxic impurities such as certain perfluoroolefins and perfluorochloroolefins may form. These impurities may be hazardous to persons handling the liquid or operating equipment containing the contaminated liquid.
For example, perfluoroisobutylene (hereinafter, for brevity referred to as PFIB) is a colorless gas at room temperature and is widely recognized as a toxic material, Exposure of persons to even low concentrations of PFIB may be lethal (e.g., Turbini, L. J., Zado, F. M., "Chemical and Environmental Aspects of Condensation Reflow Soldering", Electronic Packaging and Production, Vol. 20 (1980), Smith, L. W., Gardener, R. J., and Kennedy, G. L. Jr., "Short Term Inhalation Toxicity of Perfluoroisobutylene", Drug and Chemical Toxicology, Vol. 5, (1982) pp. 295-303, Danishevskii, S. L., and Kochanov, M. M., "Toxicity of Some Fluoro-Organic Compounds", Oigiena Truds i Professional'aye Zebeleveniay, vol. 5, (1961) and Waritz, R. S., and Kwon, B. K., "The Inhalation Toxicity of Pyrolysis Products of Polytetrafluoroethylene Heated Below 500 Degrees Centigrade", American Industrial Hygiene Association Journal, Vol. 29 (1968).
Various methods have been suggested for reducing the hazard of PFIB exposure of operators of equipment that produce PFIB (Turbini, L. J., Zado, F. M., "Chemical and Environmental Aspects of Condensation Reflow Soldering", Electronic Packaging and Production, Vol. 20 (1980), "Fluorinert.TM. Liquids", 3M Publication No. 98-0211-4411-2(78.2)R1 XY). Some of these methods include techniques of operating and maintaining vapor-phase soldering equipment to avoid superheating perfluorinated liquids, thus reducing the amount of PFIB produced, and standards of designing work areas to provide sufficient ventilation to maintain PFIB levels at less than hazardous levels. However, maintenance and operating techniques probably cannot completely prevent the formation of PFIB, and venting PFIB to the atmosphere is not environmentally desirable. U.S. Defensive Publication T983,009 (Treat) describes a method of converting PFIB in a mixture of fluorine-containing compounds into a nontoxic ether by contacting the mixture with a solution of methanol and a selected hydrogen halide. While this method does produce products which are generally less toxic than PFIB, it has disadvantages, including 1) being complex to operate in a continuous mode, since various feed streams of reactants must be controlled, 2) use of hazardous hydrogen halides (e.g., HF and HCl) as reactants and 3) yielding products which may create a disposal problem. U.S. Pat. No. 3,696,156 (Weeks) describes a method of removing perfluoroolefins and perfluorochloroolefin impurities from saturated fluoroperhalocarbon compounds having two to six carbon atoms, by contacting the impure fluoroperhalocarbon in the vapor phase at about 180.degree. to 250.degree. C. with alumina containing a basic alkali metal or alkaline earth metal hydroxide or oxide. One of the disadvantages of this process is that it requires handling hot gas contaminated with hazardous compounds.
Thus, it would be useful to develop a process to remove perfluoroolefin and perfluorochloroolefin impurities from fluoroperhalocarbon compounds that permitted purification of the compounds in their liquid state at lower temperatures.